Conventional tensile structures and tents that span large areas must be fabricated in modules to facilitate transport and handling. Modularization of the membrane presents challenges for joining it into one weather-proof membrane. Field joints are generally labour intensive, prone to leaking, and often unsightly. Field joint covers made to weatherproof lace line and other joints often employ hook and loop fasteners (i.e. Velcro) or snap, hook, and cable fasteners which are extremely sensitive to accurate indexing and almost always set up conditions for shear forces to present wrinkles along the seam cover material. Fabric joints on frame tents are made at the beams and are often prone to leaking water. However, such beams are not used in a pole supported tent, necessitating beam-free joints.
A keder, or keder strip, is a thickened edge on a membrane such as a sail, tent canopy, etc., which, when inserted into an extrusion made to accommodate it, (e.g. a keder extrusion, keder beam or keder rail) serves to fix the membrane to the extrusion. The keder extrusion has at least one channel, having a narrowed elongated opening, that receives the keder. Since the width of the keder is greater than that of the elongated opening, the only way it can be inserted or removed is to slide the keder along the channel and out one of the ends. The keder beam, rail or extrusion made to hold the keder can be made from any one of a variety of materials, but lately extrusions are considered to be the favored option.
The use of keder extrusions to join tent membranes is known in the art. However, their use is limited because they are prone to leaking. This makes keder extrusion particularly unsuitable for joining tent canopy modules at low points of a tent canopy. For this reason keders are not used to join membranes in canopy “valleys”.
As well, the height of a pole tent is dictated by the minimum slope acceptable to ensure proper drainage. The minimum slope is found on the fall line at the corners of rectangular tents. The wider the tent, the higher the peak(s) required to maintain the minimum acceptable corner slope. Higher peaks require longer poles and/or beams, adding to the weight, size and cost of the tent. It also means that the tent is more vulnerable to wind, therefore requiring more anchorage, thereby further increasing the weight, size and cost of the tent.
Accordingly, it is an object of the present invention to provide a tent structure with an effective membrane joining system that is easy to manufacture and erect. It is a further object to provide a tent with low wind profile. It is a further object of this invention to provide a tent with excellent water shedding and drainage characteristics. It is a further object to provide a tent with fabric tensioned to the level of permanent tensile structures without the complex mechanical devices and means to erect it, but instead with a simple mechanical means to introduce said tension in a safe manner by only one person. It is a further object of this invention to provide a tent with minimal ground anchorage and maximum span between side posts.